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-   -   Why is DAR wrong, VirtualDub capture from VC500? (http://www.digitalfaq.com/forum/video-capture/11268-dar-wrong-virtualdub.html)

burt8810 12-12-2020 04:12 PM

Hello, Puzzled by data from "mediainfo".
Setup1: VCR->Diamond VC500->PC via USB; Using Vdub
Device=Conexant Polaris Video Capture (Direct Show)
Video=preview
Video Source=Video Composite
Capture Pin=NTSC_M FR=29.970; Color Space=UYVY; Output Size=720x480
Compression=Huffyuv v2.1.1
Set Custom Format=720x480 UYVY YUV4:2:2 interleaved

I don't understand why the "Display aspect ratio" = 3:2

Looking at with VLC, MVP fullscreen it looks/measures 3:2.

Code:

General
Complete name                            : H:\Video\From 8mm Film.avi
Format                                  : AVI
Format/Info                              : Audio Video Interleave
Format profile                          : OpenDML
File size                                : 16.7 GiB
Duration                                : 31 min 54 s
Overall bit rate                        : 74.8 Mb/s

Video
ID                                      : 0
Format                                  : HuffYUV
Format version                          : Version 2
Codec ID                                : HFYU
Duration                                : 29 min 40 s
Bit rate                                : 80.3 Mb/s
Width                                    : 720 pixels
Height                                  : 480 pixels
Display aspect ratio                    : 3:2
Frame rate                              : 29.970 (30000/1001) FPS
Standard                                : NTSC
Color space                              : YUV
Chroma subsampling                      : 4:2:2
Bit depth                                : 8 bits
Scan type                                : Interlaced
Bits/(Pixel*Frame)                      : 7.748
Stream size                              : 16.6 GiB (100%)

Setup2:  VCR->SonyTRV480 camcorder->PC via Firewire; Using WinDV
General
Complete name                            : H:\Video\From 8mm Film_DV.20-12-11_20-22.00.avi
Format                                  : AVI
Format/Info                              : Audio Video Interleave
Commercial name                          : DVCPRO
Format profile                          : OpenDML
File size                                : 8.42 GiB
Duration                                : 41 min 46 s
Overall bit rate mode                    : Constant
Overall bit rate                        : 28.9 Mb/s
Recorded date                            : 2020-12-11 20:22:27.000

Video
ID                                      : 0
Format                                  : DV
Commercial name                          : DVCPRO
Duration                                : 41 min 46 s
Bit rate mode                            : Constant
Bit rate                                : 24.4 Mb/s
Width                                    : 720 pixels
Height                                  : 480 pixels
Display aspect ratio                    : 4:3
Frame rate mode                          : Constant
Frame rate                              : 29.970 (29970/1000) FPS
Standard                                : NTSC
Color space                              : YUV
Chroma subsampling                      : 4:1:1
Bit depth                                : 8 bits
Scan type                                : Interlaced
Scan order                              : Bottom Field First
Compression mode                        : Lossy
Bits/(Pixel*Frame)                      : 2.357
Time code of first frame                : 00:00:52;18
Time code source                        : Subcode time code
Stream size                              : 8.40 GiB (100%)

Thanks,
Burt

-- merged --

EDIT:
I just realized 720/480 = 1.5 = 3:2 so DUH! But why is SETUP2 at 4:3 at 720/480 pixels? Or has Pixel Aspect ratio changed?
What are the optimum settings for SETUP1 ?
Again many thanks.
END EDIT:

lordsmurf 12-12-2020 06:40 PM

AVI has no AR flags.
These are not meant for watching, but archive and working/intermediary files.

mjb2019 12-13-2020 05:08 PM

AVI only supports the storage of display aspect ratio (DAR) metadata if the first 4 bytes of the file spell "AVIX" in ASCII, meaning it makes use of OpenDML extensions. Otherwise the 4th character is a space instead of an X, and DAR metadata is not supported.

Software varies widely in its support of reading and writing AVI with OpenDML extensions. Some will write ordinary AVI files, some will write the OpenDML-supporting files. Some will put the DAR info in, some won't. Some will read the DAR info, some will ignore it.

If you want to try to watch your AVIs with the correct DAR, or just want to have the correct DAR stored in them for later use (e.g to avoid having to specify it when transcoding), you can use FFmpeg to remux them into new AVIs with the OpenDML headers and DAR info added:

ffmpeg -i input.avi -c copy -aspect 4/3 output.avi


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